The present invention relates generally to the preparation of electrical conductors for termination and in particular to the preparation of jacketed multiconductor filler cable for termination and is particularly concerned with removal of the cable insulating jacket and separation of the filler from the several internal insulated conductors.
A wide variety of electrical cables are known with many different systems in use for preparing those cables for termination. As one example, rotary insulation strippers for single conductor wire are known where rotating cutters blades are moved radially to the wire by the camming of a frustum itself movable axially to the wire. Many systems have been automated with a corresponding reduction in cost due to the elimination of hand operations. In dealing with filler cable, however, the hand operations have not been heretofore entirely eliminated. Filler cable is still prepared for termination (electrical interconnection) by at least a hand operation of removing the filler material.
Filler cable is typically a jacketed cable having a nonconductive component cabled with insulated conductors to impart roundness, flexibility and/or tensile strength to the cable and this twisted nonconductive component cannot be readily separated from the insulated conductors by other than a hand operation. Extension or appliance cords having a circular cross section such as the typical vacuum cleaner cord have this filler material twisted together with the conductors to impart the roundness to the cord and termination of that cord, for example, on appliance terminals or connectors for plugging the appliance into a home outlet would be more economical if the hand operation of removing the filler material from the ends of the cord or cable could be eliminated.
Conventional wire stripping and outer jacketing equipment fall into one of two categories: those employing blades that rotate around the wire and those that employ opposing blades that close on the wire.
The opposing blade devices generally consist of two identical blades in a spaced apart relationship. The wire end is placed between the blades, the blades are caused to close on the wire and partially cut through the insulation. While the blades are closed, the wire is withdrawn, the insulation is torn through to the conductor and stripped off.
Another type of opposing blade device utilizes a pivot mount for each blade. The operator pushes the wire end against the blades causing them to pivot apart. When the wire is withdrawn, the blades close on the insulation, cut it and strip the severed portion.
The basic disadvantages of these devices are that they do not completely sever the insulation, causing a ragged edge when the stripped portion is removed as well as often stretching the insulation. Further, the straight pull on the wire during removal of the stripped portion causes the wire strands to untwist or straighten. In applications where it is necessary to assure a tight grouping of the stripped conductors, it is often necessary to tin dip the stripped ends of the wire in, for example, molten solder.
Known rotating strippers employ three blades that continuously rotate around the wire. A closing mechanism is controlled by a linkage connected to a foot pedal. The operator inserts the wire and presses the foot pedal. This causes the rotating blades to close on the wire until they contact a preset adjustable stop.
The disadvantages of this type device are that the unit must be running continuously between periods of actually performing the stripping action and further that the direct mechanical linkage required to close the blades is very limiting from an automation viewpoint.